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Medina AS, Felmy HM, Vitale-Sullivan ME, Lackey HE, Branch SD, Bryan SA, Lines AM. Iodine and Carbonate Species Monitoring in Molten NaOH-KOH Eutectic Scrubber via Dual-Phase In Situ Raman Spectroscopy. ACS Omega 2022; 7:40456-40465. [PMID: 36385882 PMCID: PMC9647834 DOI: 10.1021/acsomega.2c05522] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 10/14/2022] [Indexed: 06/16/2023]
Abstract
Molten hydroxide scrubbing of off-gas vapors is a potential process to improve safety during the operation of generation IV molten salt nuclear reactors (MSRs). MSRs produce off-gases that can be vented by the reactor core and treated via off-gas scrubbers. Molten hydroxide scrubbers focus on capturing volatile iodine radionuclides, and they can also be used to capture aerosols and particulates and to neutralize acidic species. The performance of these scrubbers depends on the chemical interactions of the scrubbing medium with the off-gas species. Knowledge of the concentration and speciation of scrubbed or target species, as well as process and environmental interferents, can enable advanced operation of MSR off-gas treatment systems. Optical online monitoring is an excellent technology to provide this information in real time, while limiting the need for operators to interact with radioactive samples through hands-on interrogation. Raman spectroscopy can provide crucial chemical information on the state of the molten eutectic during treatment in the molten phase, as well as the gas phase. In this work, Raman spectroscopy is used to detect iodine species, specifically iodate, in the molten phase of a NaOH-KOH eutectic and to construct a calibration curve of the Raman signal of those species. Additionally, a carbonate interferent is followed from the gas phase to the liquid phase as a basis for reaching a Raman-aided mass balance of the molten hydroxide eutectic scrubber system.
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Carrieri D, Jurista T, Yazvenko N, Schafer Medina A, Strickland D, Roberts JM. Overexpression of NblA decreases phycobilisome content and enhances photosynthetic growth of the cyanobacterium Synechococcus elongatus PCC 7942. ALGAL RES 2021. [DOI: 10.1016/j.algal.2021.102510] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Felmy HM, Clifford AJ, Medina AS, Cox RM, Wilson JM, Lines AM, Bryan SA. On-Line Monitoring of Gas-Phase Molecular Iodine Using Raman and Fluorescence Spectroscopy Paired with Chemometric Analysis. Environ Sci Technol 2021; 55:3898-3908. [PMID: 33411509 DOI: 10.1021/acs.est.0c06137] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Molten salt reactors (MSRs) have the potential to safely support green energy goals while meeting baseload energy needs with diverse energy portfolios. While reactor designers have made tremendous strides with these systems, licensing and deployment of these reactors will be aided through the development of new technology such as on-line and remote monitoring tools. Of particular interest is quantifying reactor off-gas species, such as iodine, within off-gas streams to support the design and operational control of off-gas treatment systems. Here, the development of advanced Raman spectroscopy systems for the on-line analysis of gas composition is discussed, focusing on the key control species I2(g). Signal response was explored with two Raman instruments, utilizing 532 and 671 nm excitation sources, as a function of I2(g) pressure and temperature. Also explored is the integration of advanced data analysis methods to enable real-time and highly accurate analysis of complex optical data. Specifically, the application of chemometric modeling is discussed. Raman spectroscopy paired with chemometric analysis is demonstrated to provide a powerful route to analyzing I2(g) composition within the gas phase, which lays the foundation for applications within molten salt reactor off-gas analysis and other significant chemical processes producing iodine species.
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Affiliation(s)
- Heather M Felmy
- Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Andrew J Clifford
- Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Adan Schafer Medina
- Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Richard M Cox
- Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Jennifer M Wilson
- Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Amanda M Lines
- Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Samuel A Bryan
- Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
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Medina AS, Tibbits G, Wall NA, Ivory CF, Clark SB, Beyenal H. Electrochemical precipitation of neptunium with a micro electrochemical quartz crystal microbalance. J Radioanal Nucl Chem 2020; 324:1021-1030. [PMID: 32601515 PMCID: PMC7323927 DOI: 10.1007/s10967-020-07138-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Indexed: 11/29/2022]
Abstract
Microliter volumes are used in electrochemical detection and preconcentration of radionuclides to reduce the dose received by researchers and equipment. Unfortunately, there is a lack of analysis of radionuclides with coupled electrochemical techniques and microliter volume reactors. The goals of this work are 1) to develop a miniaturized micro-electrochemical quartz crystal microbalance (µeQCM) reactor for use in small volume (50-200 µL) electrogravimetric experiments and 2) to use this reactor to characterize the preconcentration of neptunium on carbon electrodes via electroprecipitation. We successfully deposited neptunium in the new µeQCM reactor and verified its operation. We found that preconcentration of neptunium on carbon coated electrodes was possible by chronoamperometry at -1.6 VAg/AgCl. The mass shift of the resulting precipitate was indicative of the amount of neptunium on the electrode, although the correlation between the mass increase and activity of the preconcentrated material was not linear. Neptunium precipitate reduced electron transfer to the solution as evidenced by the increase in charge transfer resistance compared to bare electrodes.
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Affiliation(s)
- Adan Schafer Medina
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, USA
| | - Gretchen Tibbits
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, USA
| | - Nathalie A. Wall
- Department of Materials Science & Engineering, University of Florida, Gainesville, FL
| | - Cornelius F. Ivory
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, USA
| | - Sue B. Clark
- Department of Chemistry, Washington State University, Pullman, WA, USA
- Pacific Northwest National Laboratory, Energy & Environment Directorate, Richland, WA, USA
| | - Haluk Beyenal
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, USA
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Medina AS, Wall NA, Ivory CF, Clark SB, Beyenal H. Preconcentration mechanism of trivalent lanthanum on eQCM electrodes in the presence of α-hydroxy isobutyric acid. J Electroanal Chem (Lausanne) 2020; 857. [PMID: 34305495 DOI: 10.1016/j.jelechem.2019.113731] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Electroprecipitation can be used to preconcentrate lanthanum on carbon electrode surfaces. The use of complexing ligands is expected to improve the electroprecipitation of lanthanum by protecting La ions in solution from the alkaline region near the electrode surface. However, the electroprecipitation mechanism of La in the presence of a complexing ligand is not known. The goal of this work is to 1) determine the effect of the complexing ligand, α-hydroxy isobutyric acid (HIBA), on the electroprecipitation of La onto the gold electrodes, and 2) identify the changes in the mechanism of accumulation when preconcentrating in the presence of HIBA. We used an electrochemical quartz crystal microbalance (eQCM) and needle type pH microelectrodes to determine pH near the electrode surface in combination with cyclic voltammetry to understand the electroprecipitation mechanism. We used the bi-dentate ligand HIBA as a ligand and found that lanthanum electroprecipitation is hindered in the presence of HIBA. The presence of HIBA also delayed the onset of film formation during a cyclic voltammetric experiment by ~100 mV compared to experiments performed without HIBA. The shift in onset potential is attributed to the buffering action of HIBA (pKa = 3.7) since the shift is not present in subsequent scans. The precipitated film was characterized by scanning electron microscopy, X-ray photoelectron spectrometry, and Auger nanoprobe spectrometry. While we found that La(OH)3 was the predominant chemical state of the film on electrodes in the absence of HIBA, La2O3 was found for films created in the presence of HIBA. Our finding demonstrates that La(OH)3 can be electrodeposited at room temperature.
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Affiliation(s)
- Adan Schafer Medina
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, USA
| | - Nathalie A Wall
- Department of Chemistry, Washington State University, Pullman, WA, USA
| | - Cornelius F Ivory
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, USA
| | - Sue B Clark
- Department of Chemistry, Washington State University, Pullman, WA, USA
- Pacific Northwest National Laboratory, Energy & Environment Directorate, Richland, WA, USA
| | - Haluk Beyenal
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, USA
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Molina DE, Medina AS, Beyenal H, Ivory CF. Design and Finite Element Model of a Microfluidic Platform with Removable Electrodes for Electrochemical Analysis. J Electrochem Soc 2019; 166:B125-B132. [PMID: 31341328 PMCID: PMC6656400 DOI: 10.1149/2.0891902jes] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A microfluidic platform for hydrodynamic electrochemical analysis was developed, consisting of a poly(methyl methacrylate) chip and three removable electrodes, each housed in 1/16" OD polyether ether ketone tube which can be removed independently for polishing or replacement. The working electrode was a 100-μm diameter Pt microdisk, located flush with the upper face of a 150 μm × 20 μm × 3 cm microchannel, smaller than previously reported for these types of removable electrodes. A commercial leak-less reference electrode was utilized, and a coiled platinum wire was the counter electrode. The platform was evaluated electrochemically by oxidizing a potassium ferrocyanide solution at the working electrode, and a typical limiting current behavior was observed after running linear sweep voltammetry and chronoamperometry, with flow rates 1-6 μL/min. While microdisk channel electrodes have been simulated before using a finite difference method in an ideal 3D geometry, here we predict the limiting current using finite elements in COMSOL Multiphysics 5.3a, which allowed us to easily explore variations in the microchannel geometry that have not previously been considered in the literature. Experimental and simulated currents showed the same trend but differed by 41% in simulations of the ideal geometry, which improved when channel and electrode imperfections were included.
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Abstract
A cross-sectional study of 194 adolescents in Alameda County, California, was performed to investigate health care behavior, personal adjustment, substance abuse, and medical and dental morbidity. A multivariate analysis of this sample using age, sex, ethnic group, and family type as independent variables was carried out. Females were less likely than males to have a regular place for medical care, and youths belonging to single parent families were less likely than those from intact families. Older adolescents, blacks and Hispanics used hospitals and clinics more frequently, while whites used private physicians more frequently than did other ethnic groups. Also blacks and Hispanics were less likely to have received recent dental care than whites. Levels of substance abuse were comparable to national levels, and increased significantly with age. Though overall medical morbidity was low, the study confirms previous findings of significant levels of dental decay particularly in black youth. A significant relation exists between less dental care and dental decay, though no such relation exists between medical care and medical morbidity. The study has potential implications for better preventive approaches to adolescent health care.
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Medina AS. Hispanic maternity care: a study of deficiencies and recommended policies. Public Aff Rep 1980; 21:1-7. [PMID: 10248174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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